For example, a pressurized water reactor (PWR: Pressurized Water Reactor), using light water as a reactor coolant and a neutron moderator, runs it as non-boiling, high-temperature and high-pressure water throughout a reactor core, sends the high-temperature and high-pressure water to a steam generator for generation of steam by heat exchange, and sends the steam to a turbine generator for generation of electricity. The pressurized water reactor transfers the heat of high-temperature and high-pressure primary cooling water to secondary cooling water by way of the steam generator, generating the steam from the secondary cooling water. In the steam generator, the primary cooling water flows inside a large number of narrow heat-transfer tubes, and the heat of the primary cooling water is transferred to the secondary cooling water flowing outside the heat-transfer tubes, thereby generating the steam, which causes the turbine to rotate for generating electricity.
In the steam generator, a tube bank external cylinder is arranged inside a sealed hollow barrel with a predetermined space from the inner wall thereof, a plurality of heat-transfer tubes of an inverted U shape are arranged inside the tube bank external cylinder, with each heat-transfer tube having its end supported by a tube support and its middle part supported by a plurality of tube supporting plates that are supported by stay-rods extending from the tube support, and an incoming water chamber and an outgoing water chamber are formed at the lower end of the barrel.
Therefore, the primary cooling water is supplied from a cooling water pipe to the plurality of heat-transfer tubes through the incoming water chamber, while the secondary cooling water is supplied to the inside of the barrel from a water supply pipe provided at the upper part of the barrel. Then, heat exchange is performed between the primary cooling water (hot water) flowing inside the plurality of heat-transfer tubes and the secondary cooling water (cold water) circulating inside the barrel, so that the secondary cooling water absorbs the heat and the steam is generated. Then, the generated steam is discharged from the upper end of the barrel, while the primary cooling water after the heat exchange is discharged from the outgoing water chamber to the cooling water pipe.
This type of steam generator is described in Patent Document 1.
Patent Document 1: Japanese Patent Application Laid-Open No. H01-235897